from PyQt5.QtWidgets import QApplication, QVBoxLayout, QPushButton, QWidget

class MainWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Layouts Example")
        self.setGeometry(100, 300, 800, 600)

        layout = QVBoxLayout()
        layout.addWidget(QPushButton("Button 1"))
        layout.addWidget(QPushButton("Button 2"))
        layout.addWidget(QPushButton("Button 3"))

        self.setLayout(layout)

if __name__ == "__main__":
    app = QApplication([])
    window = MainWindow()
    window.show()
    app.exec()
